1. Field of the Invention
This invention relates generally to automated data-storage libraries and, in particular, to a lockout mechanism for ensuring that a data cartridge is inserted correctly into the receiving cell of the input/output station of a library.
2. Description of the Related Art
The portability of magnetic tape cartridges makes it possible to store them in readily accessible multi-cell libraries, so that large amounts of data can be saved and retrieved at will using automated equipment. When, for example, a particular cartridge is required for use in a computer""s I/O device, the unit is retrieved by a robot from the cell where it has been stored in a library and it is automatically loaded for processing.
Cartridges are initially placed into libraries manually through input/output stations which consist of stacks of individual through-slots with an exterior opening adapted to receive a cartridge of a predetermined size and configuration. For example, FIG. 1 illustrates an IBM 3584 Automated Library that incorporates an I/O station 10 with a cartridge 12 inserted half-way into a receiving through-slot 14. Each slot has also an interior opening (not shown) through which the cartridge is removed by a robot for automated placement in a library storage cell or magazine. The picker mechanism through which each cartridge is transferred includes gripper arms that hold the cartridge and guide it in and out of the I/O station, and similarly in and out of the library cell, computer peripheral, or other device being used. The cartridges have retaining features that permit gripper arms to latch on to the cartridge by means of appropriate locating and gripping notches or equivalent structural features built into the case of the cartridge. Accordingly, commercial cartridge formats are standardized to provide uniformity of construction and interchangeability of operation between cartridges produced by different manufacturers.
In operation, each cartridge 12 is initially inserted manually by an operator into a slot 14 of a receiving cell in the I/O station. The cartridge must be positioned correctly in order for the gripper arms to be able to retrieve it from the other side of the cell. Thus, only one of the eight possible orientations of a conventional cartridge is acceptable for the picker mechanism inside the library and any other orientation of the cartridge would be incorrect and cause a failure of the automated system. The problem is worse with libraries that operate with multiple types of cartridges and that, therefore, provide an even smaller ratio of correct options. If two formats are used, for example, only one out of sixteen possible alternatives is correct.
Two of the cartridge formats most widely used currently around the world are the so called DLT (digital linear tape) and LTO (linear tape open) formats, each characterized in detail by corresponding ECMA (European Computer Manufacturers Association) 286 and 319 standards. Accordingly, IBM""s 3584 Library accommodates both types of cartridge and is equipped with corresponding I/O units with cells selectively dedicated to one cartridge or the other. Each cartridge format features prescribed structural attributes adapted to function with conforming standard features in the automated mechanisms of a corresponding drive, picker and library system. For example, a typical DLT format cartridge 20, such as IBM(copyright)""s DLTtape(copyright) IV Cartridge illustrated in FIG. 2, is characterized by a hinged door 22 on the front side 14 of the cartridge. When the DLT cartridge is inserted into a drive, a stationary device penetrates a gap 26 in the door hinge 28 and presses against a spring-loaded latch 30 to automatically release the door 22 and swing it open toward the front of the cartridge. As a result, the tape""s leader inside the cartridge (not seen) can be accessed by the drive""s mechanism. As the door 22 opens, the door hinge 28 rotates inwardly toward the right side 32 of the cartridge. Accordingly, the right side of the DLT cartridge 20 features a progressively deepening cavity 34 designed to accommodate the door hinge 28 when the door 22 is fully open. The shallower portion of the cavity 34 also features two ribs 36.
Thus, the right side 32 of the DLT cartridge contains several pronounced structural features that distinguish it from all other sides, as well as from every side of the LTO cartridge. When a DLT cartridge is inserted in an I/O station by an operator, it must be placed top-side up and with the door 22 facing the exterior of the station, as illustrated in FIG. 3; otherwise, the library picker cannot properly grab and retain the cartridge, and the picker may become disabled causing the automated library to go off-line and the stored data to become inaccessible. This possibility of failure is unacceptable in today""s world of uninterrupted-service demand. Therefore, it would be very desirable to have a mechanism that prevents the incorrect placement of a DLT cartridge or the placement of another cartridge into the receiving slots of an I/O station designed to handle only DLT cartridges.
U.S. Pat. No. 6,141,180, issued to Smith, describes a pivoting lockout that prevents the incorrect placement of a DLT cartridge into a receiving device, such as a tape magazine, a library or a mail slot. The lockout consists of a hinged member with a leading and a trailing edge protruding into the sleeve to be occupied by the cartridge when it is placed in the receiving device. Therefore, the cartridge can be successfully introduced into the device only one way, when the side containing the cavity is facing the hinged lockout member. Because of its configuration and placement, the lockout member is able to clear the ribs 36 and to fit into the cavity 34 of the DLT cartridge (refer to FIG. 2 above) as the cartridge is pushed into the sleeve of the receiving device. Thus, the lockout of the invention prevents the complete insertion of the DLT cartridge unless it is oriented correctly.
The Smith lockout device is not designed for a pass-through sleeve of the type present in I/O stations. It is only concerned with ensuring that the cartridge is placed correctly in a receiving cell from which it is to be extracted later in reverse direction. Accordingly, the door hinge 28 could not clear the two protruding edges of the lockout if the cartridge were to be extracted in pass-through fashion from the interior side of an I/O station. The present invention provides a new design for a lockout mechanism that overcomes this problem and is therefore suitable for use in input/output stations.
The primary objective of this invention is a lockout mechanism that allows the complete introduction of a DLT cartridge into an I/O station only when it is properly oriented.
Another objective of the invention is a lockout mechanism that permits the pass-through extraction of the DLT cartridge from the interior side of the I/O station by an automated library picker.
A specific goal of the invention is a lockout mechanism that also prevents the full insertion of an LTO cartridge into the DLT I/O cell of an IBM 3584 Library.
Finally, an important goal of the invention is a lockout mechanism that can be easily incorporated into the structure of existing I/O stations of automated libraries.
Therefore, according to these and other objectives, the invention consists of a two-lever toggle mechanism designed to operate in conjunction with the conventional toggle bracket of I/O stations in automated libraries. Each lever of the toggle mechanism is mounted on one of the two side posts that support each receiving slot of a conventional I/O station. The front lever is rotatably mounted on the front post and includes a leading blade or structural protrusion facing the slot and a front wing that cooperates with the toggle bracket provided to control access to the I/O station. When the toggle bracket is closed, access to the I/O station is prevented by the encroachment of the front edge of the bracket over the opening of the I/O slots. In such closed position, the leading protrusion of the front lever rests inside the slot of the cartridge. When the toggle bracket is opened to permit manual access to the I/O station to either insert or remove cartridges, the toggle bracket causes the front lever to rotate to an open position whereby the leading protrusion is removed from the slot of cartridge. As a result, the leading protrusion does not obstruct the introduction of any appropriately sized cartridge into the slot. When an LTO cartridge or a DLT cartridge in the wrong position is introduced into the slot, the counter-rotation of the front lever required to permit the closure of the toggle bracket is blocked by the substantially flat side of the cartridge that faces the leading protrusion and prevents its penetration into the slot. Therefore, the I/O station cannot be closed. When, instead, a DLT cartridge is introduced in the correct orientation, a cavity in the side of the cartridge is able to accommodate the leading protrusion of the front lever as it is being pushed into the slot by the closing motion of the toggle bracket. Therefore, according to one aspect of the invention, only a DLT cartridge that is placed correctly into the slot permits the closure of the toggle bracket of the I/O station. Accordingly, this feature provides immediate notice to an operator when he or she introduces the wrong cartridge or the wrong side of a DLT cartridge into a DLT I/O unit of an automated library.
According to another aspect of the invention, the toggle mechanism also includes a rear lever rotatably mounted behind the front lever on the rear post of each slot. The rear lever incorporates a trailing protrusion facing the slot and a shank slidably coupled to an elongated groove in the front lever. When the front lever is in closed position with the leading protrusion resting in the slot, the connection between the elongated groove and the shank causes the rear lever to be also closed with the trailing protrusion encroaching into the slot. When the toggle bracket is opened and the front lever rotates around the front post to an open position, the corresponding motion of the elongated groove causes the shank and rear lever to also rotate around the rear post to an open position whereby the trailing protrusion is withdrawn from the slot. As a result, both the leading and trailing protrusions are out and any appropriately sized cartridge can be introduced into the slot. When the toggle bracket is closed, by virtue of the groove/shank connection, the front and rear levers counter-rotate together causing both the leading and trailing protrusions to protrude into the cartridge slot. If an LTO cartridge or a DLT cartridge in the wrong position is in the slot, the counter-rotation of the front and rear levers is blocked by the leading and trailing protrusions because they both butt against the side of the cartridge in the slot. On the other hand, when a DLT cartridge is introduced in the correct orientation, the cavity in the side of the cartridge is able to accommodate both protrusions. Therefore, the trailing protrusion provides an additional safeguard to ensure that only a DLT cartridge that is placed correctly into the slot permits the closure of the toggle bracket.
According to yet another feature of the invention, the elevational position and the maximum degree of penetration of the leading and trailing protrusions are selected such that both protrusions clear the gap in the door hinge of the LTO cartridge when the cartridge is removed by the library robot from the interior side of the I/O station. Thus, only a properly positioned LTO cartridge can be successfully loaded into the exterior side of the I/O unit of the library and removed from the interior side by a library robot.
Various other purposes and advantages of the invention will become clear from its description in the specification that follows and from the novel features particularly pointed out in the appended claims. Therefore, to the accomplishment of the objectives described above, this invention consists of the features hereinafter illustrated in the drawings, fully described in the detailed description of the preferred embodiment and particularly pointed out in the claims. However, such drawings and description disclose only some of the various ways in which the invention may be practiced.